The approval process for a massive Alaska oil drilling project sparked intense disagreements within the Biden administration that culminated with a tactful media leak late last week, according to two senators who advocated for the project.

President Joe Biden and senior White House advisers ultimately made the call to green-light the Willow Project, a drilling project that its developer, ConocoPhillips, forecasted to produce up to 614 million barrels of crude oil over its 30-year lifespan, but faced stiff opposition from officials elsewhere in the administration, Alaska Republican Sens. Lisa Murkowski and Dan Sullivan told reporters during a call Monday.

"Were there people within the administration, within the Department of Interior, that were working to actively kill this? Absolutely, positively," Murkowski said. "I don't think you have to name names. Let's just put out there that this administration has made no secret of the fact that they want to move beyond oil."

"There are absolutely people in the administration today who are not viewing this as good news," she continued. "I think they tried to actively work against us, and they worked against us right up until the end."

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Climate activists hold a demonstration to urge President Biden to reject the Willow Project at the Department of the Interior headquarters on Nov. 17 in Washington, D.C.

Several officials within the Biden administration were said to be actively working to reverse an internal decision to move forward with the Willow Project. (Jemal Countess / Getty Images for Sunrise AU)

Murkowski, Sullivan and Alaska Democratic Rep. Mary Peltola had repeatedly urged the administration over the course of the last year to approve the project, noting that it had near unanimous support throughout Alaska and arguing that it would provide a much-needed boost to the state's economy while bolstering U.S. energy security.

The Department of Interior (DOI) published its decision Monday morning, approving three of five proposed drilling sites in a major victory for its proponents and a cause for consternation among environmentalists who said the project was a "carbon bomb." Interior Secretary Deb Haaland notably didn't provide a statement in the public announcement.

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"I think we realized some time ago that this was going to be a decision that was ultimately made at the White House level, not only by senior leaders but actually with the president's direct involvement himself," Murkowski told reporters. "The president had clearly been apprised of Willow and what Willow was."

"This was not something that I think was ultimately going to reside with the secretary of Interior."

Sen. Lisa Murkowski

Sen. Lisa Murkowski speaks during a Senate hearing on May 18, 2022. (Bill Clark / CQ-Roll Call Inc. via Getty Images)

Sullivan added that he knew "for a fact" the decision to approve Willow was leaked late last week in a last-ditch effort to change Biden's mind by those in the administration opposed to the project. Bloomberg first reported Friday evening that senior administration officials had signed off on the project.

The report was quickly followed by a statement from White House press secretary Karine Jean-Pierre that a decision had not been made and that "anyone who says there has been a final decision is wrong."

Sen. Dan Sullivan, R-Alaska

Sen. Dan Sullivan, R-Alaska, speaks during a Senate Environment and Public Works Committee hearing on May 20, 2020. (Al Drago / Pool / Getty Images)

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"We know, for example, for a fact that the leak to the Bloomberg reporters on Friday was an attempt by certain anti-Willow forces in the Biden administration to kill the project," Sullivan said Monday. "That was disappointing to see that. We were very aware of that from the beginning."

"Secretary Haaland has not been actively engaged, in my view, at all on this," he continued. "And that may have been from the fact that she, as a congresswoman, was vocally against Willow. So, it probably wouldn't have been objective to have her be the decision maker. It was clearly at the presidential level."

The DOI declined to comment. The White House didn't immediately respond to a request for comment.